Dresser compensating mechanism for grinding machines



Oct 30, 1945. A. F. MARKUS 2,388,065

DRESSER COMPENSATING MECHANISM FOR GRINDING MACHINES Filed Aug. 28, 1944 4 Sheets-Sheet 1 Filed Aug. 28, 1944 .4 She ets-Sheet 2 1 55 k N 4 1! N '51 V s V i v V 21 M Q W 3L W a; i2- 2'% $15 v- M v nii 2 m l. Q n g 8 3 L Oct. 30, 1945. F, us 2,388,065

DRESSER COMPENSATING MECHANISM FOR GRINDING MACHINES 8 a3, Wop

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Oct. 30, 1945. A. F. MARKUS 2,388,065

DRESSER CQMPENSATING MECHANISM FOR GRINDING'MACHINES Filed Aug. 28, 1944 4 Sheets-Sheet s Patented on; so, 1945 1UNlTED STATES PATENT OFFICE DRESSER COMPENSATING MECHANISM FOR GRINDING MACHINES sum F. Markus, Detroit, Micln, assignor to Ex- Cell- Corporation Detroit, Mich., a corporation of- Michigan Application August 28, 1944, Serial No. 551,477

13 Claims. (01. 51-95) The present invention is intended tor application to grinding machines such, for example, as thread grinders, and has particular reierence to grinding machines incorporating that general class or mechanisms known as automatic dressing compensators which serve to modify autoscription proceeds, taken in connection with the accompanying drawings in which:

matically the relative displacement of grinding wheel and work by an amount requisite to compensate for the diminishment in wheel'size necessarily incident to each truing or dressing of the same.

The general aim of the invention is to provide in a grinding machine such a mechanism, andcoacting size control device, embodying a novel and simplified combination of elements suchas to aflord high precision results while utilizing rugged, simple and comparatively inexpensive In carrying out the present invention, I preferably utilize the displacement of a. nut, in a direction axially of a shaft on which it is threaded, to move the work support relative to its associated grinding wheel. The movement of the nut may be accomplished in such case either by shitting the shaft bodily in an axial. direction or r by revolving'such shaft so that the nut is threaded along it. A more specific object of the present invention is to provide a novel and improved arrangement in which bodily axial shifting of a such shaft is eiiected in response to movement of a dresser mechanism, whereas rotation of the shaft is accomplished in response to actuation of a size control device. Accordingly, movement of other of the pair in such manner as to effect compensation for dressing, together with means including a piston and cylinder type actuator interposed in such mechanical interconnection for eiiecting rapid shift of said one support with reference to the other of the first-mentioned pair without moving said dresser support.

Further obiects and advantages of the inven tion will become apparent as the-following d0? Figure 1 is a front elevation of a thread grinding machine embodying the present invention.

Fig. 2 is an enlarged detail sectional view taken longitudinally through the work support of the machine of Fig. 1. a

Fig. 3 is a sectional view taken from front to rear through the upper portion of the machine.

substantially along the lines 3-8 in Fig. 1.

Fig. 4 is a more or less diagrammatic view similar to Fig. 3 but showing the dresser supporting arrangement in section. t

Fig. 5 is. a'detail sectional view taken substantially along the line 5-5 in Fig. 4.

Fig. 6 is a detail perspective view of a portion of the adjustable mount for the wheel support.-

While the invention is susceptible of various modifications and alternative constructions, I

have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications Y and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring more particularly to the exemplary embodiment of the invention illustrated in the drawings. the thread grinding machine there 'shown comprises a base or bed ID on the top of which are work and grinding wheel supports ll and II, respectively (Fig. 1). The latter carries a rotatively driven grinding wheel H. In the particular machine chosen for purposes oi illustration, both therelative traversing motion of such supports'axially of the work in timed relation with the latter's rotation. and the incremental transaxial relative infeed movement of such supports, normally incident to thread grinding, are accomplished by imparting corresponding appropriate motions to the work support ii, the wheel support It remaining stationary throughout the normal operation. In its broader aspects.

however. the invention is applicable to grinding. machines in which that same relativity 01 motion is accomplishedin other manners.

The present invention is concerned primarily with an arrangement for modifying automatically the transaxial displacement of grinding wheel and work to compensate for diminutions in grinding wheel diameter incident to dressing or truing of the wheeLby suitable truing means such as the dresser indicated at il- (Fig. 3). In the illustrative machine such compensatingmotion is imof a work piece W carried between centers I9, 20 I on the support. The frame I6 is rocked or pivoted about these same guide bars I1, IE to move the work transaxially toward and from the grinding wheel I4. To suitably mount the frame for such motions, depending feet 2|, 22 integral with the frame I6 are -journaled on respective ones of the guide bars I1, I8. The opposite end portions of the latter-are fixed in respective pairs of lugs 23', 24 and 25, 26 on the machine base Ill.

One of the work-receiving centers 20 (Fig. 2) is carried by a tailstock 21 adjustably slidable along the frame I6 and adapted to be clamped thereto, whereas the other center 19 is fixed in the end of a work-rotating spindle 28, the drive for which will hereinafter appear. The forward end of such spindle is journaled in an antifriction bearing 29 mounted in a wall 30 rising integrally from the frame i6 and forming the front face of a headstock casing. Such casing is completed by a detachable casing member 3I having a tubular extension 32 projecting therefrom coaxially with the spindle and carrying an antifriction' bearing 33 supporting the intermediate portion of the spindle.

The work support frame I6 rests upon, and is translatable axially along, an intermediate support 34 (Figs. 2 and 3). This intermediate support or apron comprises a generally rectangularshaped casting pivoted coaxially with the work support frame I6 on the same guide bars I1 and I8 whichcarry the latter. Upon reference to Fig.

2 it will be seen that lugs 35 and 36 on the intermediate support 34 are journaled on respective ones of these guide bars. The intermediate support is, unlike the work support frame, restrained against axial movement, however.

drive mechanism (not shown) may be housed in the casing 44 to turn the. screw incrementally in timed relation with the reciprocation of the work support II. A suitable mechanism for the purpose is disclosed in Guenther Brinkm'ann application Serial No. 435,224, filed March 18, 1942,

I and assigned to Ex-Cell-O Corporation, assignee A pair of yoke-shaped legs 31 rigid with the intermediate 1 support 34 depend from it and slidably receive laterally projecting trunnions 38 on a nut 39. The intermediate support 34, together with the work support frame I6 resting on it, is thus rocked about its pivot generally transaxially of the grinding wheel I4 uponendwise movement of the nut 39.

The nut 39 is threaded on a screw 40 formed intermediate the endsof a shaft 4 I, the nut itself being restrained against rotation by engagement of its flat sides with the legs 31 between which it is positioned (see Fig. 2). be moved endwise either by'rotation of the screw 45 or by bodily endwise movement of such screw. In the present instance the screw 46 is revolved to move the nut 39 endwise for rocking the work support for size control purposes, whereas the screw 40 is moved endwise to shift the nut and The nut may thus thus the work support for compensating purposes.

wheel.

v against endwise movement.

of this present application, but since the same constitutes per se no part of the present invention, it need not be illustrated in detail here.

To shift the screw 40 endwise proportionately to changes in wheel diameter incident to dressing of the latter, the screw is mechanically connected to a dresser supporting frame or bracket 45 (Figs. 3 and 4). The frame 45 is rigidly bolted to the underside of a dresser approach slide 46 and is movable bodily with the latter toward and from the grinding wheel in a direction generally transaxial of such wheel. To mount the slide 46 for such movement, rails 41 (see Fig. 5) are fixed in horizontal position on an upstanding rearwardly disposed portion of the wheel support I2 and have longitudinally extending grooves 48 therein. Secured to the underside of the" slide 46 is a pair of rails 49 longitudinally grooved as indicated at 50. Antifriction ball elements 5| are received between the opposed pairs ofgrooves 48, 50, the latter constituting raceways for the balls.

Any suitable form of dresser mechanism I5 7 operates through a cam 54 to cause the dresser. point 52 to execute a predetermined cycle of movement with reference to the approach slide 46 in moving the dresser point into engagement with the periphery of the grinding wheel I4 and thence away from the latter into an inoperative position again. The mean location of the path of the dresser point in each such cycle, with reference to the grinding wheel, is determined by the location of the approach slide 46 and the latter is, accordingly, advanced incrementally preparatory to each cycling of the dresser.

A dresser feed screw 55 (Fig. 4) is provided for shifting the dresser frame 45 and its attached approach slide 46 toward and from the grinding For such purpose the screw is threaded in a nut 56 rigid, with the frame 45 and is journaled in an upstanding rear portion I2a of the wheel support I2, the screw being restrained A dresser feed control wheel 51 fixed to the screw 55 may be used in rotating the latter manually. If desired, provision may also be made for effecting step-bystep turning of the screw 55 in timed relation with the cycling of the dresser mechanism I5 as, for example, through the use of a control arrangement for such purpose such as that disclosed in Ira J. Snader'Patent No. 2,251,961, issued August12, 1941. As indicated herein in Fig. 4, a ratchet wheel 58 may be fixed to the screw 55 and arranged'for actuation by a pawl 69 carried by an oscillatab le pawl carrier 50, the length of the angular distance through which the ratchet wheel is advanced upon each stroke of the pawl being determined by a pawl guard 60 adjustably held in position by a thumb screw 6|. A reciprocable plunger 62 may serve to oscillate the pawl carrier 60 through use of a control arassaoes rangement'like that disclosed in said Snader Asto the mechanical connections between the dresser supporting frame 45 and the shaft ll of the screw 49, it will be observed upon reference to Fig. 4 that a hydraulic piston and cylinder type actuator 63 is interposed between these elements, the same being provided for eflecting quick retraction of the work with reference to the grinding wheel. This actuator includes a cylinder 94 connected .by dovetail guides II with the dresser supporting frame 45 in order that the latter may be adjusted horizontally (i. e., in a direction axially of the work) with reference to the cylinder. Slidable in the cylinder 84 is a piston 88 having a socketed end 81 receiving the spherical opposed end of the screw shaft ll. Assuming pressure fluid to be supplied to the cylinder 64 through either of the ports ll, ii and exhaustedthrough the other, it will be seen that the dresser supporting frame 4! and screw ll are rigidly connected for movement in unison. Thus, upon each incremental rotation of the dresser feed screw 55 to approach the dresser supporting frame 45 toward the grinding wheel, the cylinder 64 is correspondingly thrust to the left (as viewed in Fig. 4) carrying with it the shaft 4i and screw 4|. The work piece 'W is thereby rocked toward the grinding wheel H a corresponding increment of distance, calculated through suitable dimensioning of the parts, to

relocate the work with reference to the wheel in ment is used in locating the wheel for a desired helix angle for the thread ground on the work.

disturbed with reference to the grinding wheel I 4. Movement of the dresser frame 45 laterally or. in other words, longitudinally of the work, is accommodated by the dovetail guide 55, whereas its angular movement is accommodated by the ball andsocket joint 81,. I

In the operation of the grinding machine disclosed, pressure fluid (from some suitable source, not shown) is supplied to the cylinder 84 through the port 88 to thrust the screw shaft ll leftward, therebyrocking the work picceW quickly toward the grinding wheel it. Having. thus approached the work closely adjacent ,the grinding wheel, the work support frame is reciprocated back and forth axially of the work in timed relation with rotation of the latter. In the course of such reciprocation the screw 40 is turned step by step as, for example, after each pass'of the work, until a thread of preselected depth has been ground in the work piece. At the conclusion of the grinding operation pressure fluid is admitted to the retract cylinder port 68 and exhausted through theport 69, thereby permitting.

the work support to swing gravitationally outward away from the grinding wheel while thrusting the screw shaft 4| to the right. It will be perceived that the hydraulic actuator 83 serves to rock the work support between alternate limit positions and that the size control mechanism alters the displacement of the work support with reference to the grinding wheel 14, movement of the dresser supporting frame also serving to alter or further modify suchdispla'cement.

At selected points in the grinding operation or after one or more complete grinding operations, thegrinding wheel I is trued. For that purpose the work piece W is temporarily retracted from contact with the grinding wheel 14 by the,

retract actuator. 83 and the dresser feed screw 40 It turned to advance the dresser supporting With regard to the latter, it will beunderstood that the required range of adjustment is rather small, being of the order ofiive degrees in the illustrated machine.

To mount the wheel support I! for adjustment both longitudinally of the work and angularly with reference thereto, as noted above, an inclined flat surface ll is machined on the bed II and an opposed parallel surface I9 provided on the wheel support If. A block II having parallel fiat faces is interposedbetween the surfaces ll, '0. This block is releasably clamped to the base II by bolts H having heads received in T- slots 12 extending longitudinally of the surface ll (see Fig. 6), and a key It guides the block accurately for adjustment longitudinally of such surface ll. Similarly. the wheel support I! is releasably secured by bolts passing therethrough frame II a predetermined increment of distance. Thereafter the dresser mechanism is operated, causing the dresser point or points 52 to execute a predetermined cycle of movement in which they true or dress the periphery of the grinding wheel and in doing so reduce it to a new diameter, the

magnitude of the latter being determined by the position of the dresser supporting frame 45. Coincident with the advance of the dresser supporting frame II, the screw shaft 4| is thrust to the left, thereby rocking the work piece W incrementally toward the grinding wheel a. proportionate distance. Consequently the position of the work with reference to the grinding wheel flied June 29, 1944. Accordingly, simply a brief J identification of the elements of the drive arrangement will suffice for present purposes, the

principal elements of the illustrated structure having been previously noted. Upon reference to 11g. 2 it will be seen that the work supporting spindle II is revolved by a gear 80 integral with a sleeve 'Il fixed to the spindle. Such gearme'shes with a gear I! carried by a shaft '3 fsplined at It to a shaft ll carrying a gear ll.

The latter gear meshes with a gear .1 coaxial with the guiderod ll, being carried on a. shaft .nected by a pulley 81 with a worm 82 (Fig. 2)

meshing with a worm wheel 88, rigid with the end of theshaft 88.

Axial translation of the work. in timed relation with its rotation is accomplished through the use of a master lead screw 84 (Fig. 2) keyed to the work'spindle and threaded in a nut 85. The

latter nut is fixed to the end of a sleeve 88 which normally remains stationary within a housing or head 81. The latter head has 9. depending foot 88 journaled on the guide rod 11 in order that the head 81 may rock about the axis of the guide rod coincidentally with the rocking motion of the main work supporting frame 18. A block 88 secured to the head 88 on the side of the sup" porting lug 23 opposite the foot 88 coacts with the latter, however, to restrain the head 81 against translation axially of the guide rod. The

tubular extension 82 on the housing 81 of the main work support is telescoped within the sleeve 88 and thus retains the head 81 and frame 88 in angular coincidence about the axis of the guide rod 11 while permitting relative displacement of the same axially of such guide rod. Rotational adJustment of the sleeve 88 within the head 81 to'determine the point of lead'pick-up is accom-' plished by a transverse screw I88, adapted to be turned by a handwheel I81, and meshed with an annular series of worm. gear teeth I82 formed in the periphery of the sleeve.

Provision may also be made if desired for accommodating the motion of the work to'taper grinding, relief grinding, etc. So long as these motions are imparted through movement of the work supporting frame 18 relative to the intermediate support the latter remains unaffected and there is consequently no change required in' the compensating mechanism. In the illustrated arrangement (Figs. 1 and 3) a liar' Ill is clamped to the front of the frame I 8 in adiustably variable inclined position and rests the overcharging weight of the frame 18 on the nose of a pin 1. The latter pin is carried by a bar I88 extending transversely of the intermediate support 88 and pivoted intermediate its ends to the latter on a pivot support (not shown) which is positionally nut being disposed for endwise movement with reference to said base, means mechanically connecting said work support to said nut for movement of said work support transaxiallyof said wheel in accordance with endwise movement of said nut, size control means for rotating said screw to move said nut endwise, and means connecting said dresser support to said screw for bodily endwise movement of the latter, together with said nut carried thereby, upon changs in position of said dresser support. f

2. Ina grinding machine, the combination of a base having relatively movable work and wheel supports mounted thereon, the latter carrying a rotatlvely driven grinding wheel, a dresser support mounted on said base for adjusting movement of the same toward and from said grinding wheel, a size control device, means rotatably Journaling said device on said base while restraining the same against movement longitudinally of its axis of rotation, a rotatable size control shaft having a sliding coupling with said device, means connecting said shaft'to said dresser support for bodily endwise movement of said shaft'with said dresser support, a nut threaded on said shaft and restrained against rotation. and means foreifecting relative movement of said work and wheel supports transaxially of said wheel in response to translation of said nut incident either to rotation of said shaft by said size control device or axial displacement of said shaft by said dresser support.

3. In a grinding machine, the combinationof a base having a rotatlvely driven grinding wheel thereon, work and dresser supports disposed on generally diametrically opposite sides of said wheel, means pivoting said work support on said base for rocking of said work support toward and from said wheel about an axis generally paralleling that of the latter, means mountingsaid dresser support for adjusting movement of the same toward and from saidwheel, a screw exadjustable longitudinally of the bar I" and which may, for example, be of the form detailed in my copending application Serial No. 542,719 referred to above- The bar I" is adjusted to an angle of inclination corresponding to a desired degree of taper on the work, and the bar ill is rocked by a cam I88 (driven in timed relation with rotation of the spindle) for relief purposes. Details of the arrangement are disclosed in said copending application Serial No. 542,719.

-I claim as my invention: 1

1. In a grinding machine, the combination of a base having a wheel support fixed thereon carrying a rotatlvely driven grinding wheel, a work support mounted on said base. for movement transaxially of said wheel, a dresser support also mounted on said base for adjusting movement of the same generally transaxially of said grinding wheel, a screw having a nut threadedthereon with the latter restrained against rotation, said tendihg at right angles to the pivotal axis of said work support and having a nut threaded thereon with the nut restrained against rotation,'means connecting said nut to said work support for rocking of the latter about its pivotal axis in accordance with axial displacement of said nut, size control means for rotating said screw to displace said nut axially, and means connecting said screw to said dresser support for bodily endwisemovement of said screw, together with said nut carried thereby, in accordance with movement of said dresser support.

4. In a grinding machine, the combination of a base having a rotatlvely driven grinding wheel thereon, work and dresser supports disposed on generally diametrically-opposite sides of said wheel, means pivoting said work support-on said base for rocking of said work su'pporttoward and from said wheel about an axis generally paralleling that of the latter, means mounting said dresser support for adjusting movement of the same toward and from said wheel, a screw extending at right angles to the pivotal axis of said work support and having a nut threaded thereon with the nut restrained against rotation, means connecting said nut to said work support for rocking of the latter about its-pivotal axis in accordance with axial displacement of said nut, and means connecting said screw to said dresser supportfor bodily endwise. movement of said screw, together with said nut carried thereby, in accord,- ance with movement of said dresser support, said last-mentioned means including'a cylinder having a fluid operatedpiston slidabletherein interposed between said screw and dresser support for'altering the displacement of said screw with reference to said dresser support in accordance with changes in position of said position within its cylinder;

5. In a grinding machine, the combination of a 'base having a rotatively driven grinding wheel a and from'said' wheel about an axis generally paralleling that of the latter, an intermediate support located beneath said work support with the latterresting on it, means pivoting said intermediate support on said base for rocking motion about an axis coincident with the pivotal axis of said work support by restraining said intermediate support against endwise movement, means mounting said dresser support for adjusting movement of the same toward and from said wheel, manually operable means i'or shifting said dresser support toward and from said wheel, a screw located beneath said intermediate support and disposed at right angles to the common pivotal axis of said work and intermediate supports, a nut threaded on said screw and restrained against rotation, a depending leg on said intermediate support pivotally connected to said nut, whereby endwise movement of said nut effects rocking motion of said intermediate support and the work support resting thereon, size control means for rotating said screw to displace said nut axially, and means connecting said screw-to said dresser support for bodily endwise movement of said screw, together with said nut carried thereby, in accordance with movement of said dresser support.

6. In a grinding machine, the combination of a first pair of supports adapted to carry, respectively, a work piece and a rotatively driven grinding wheel, a'base, means stationarily mounting one of said pair of supports, on said base and movably mounting the other for movement relative to the first-mentioned support in a direction transaxial of said wheel, a dresser support adlustable toward and from 'said wheel, means mechanically connecting said dresser support to the movably mounted one of said first pair of supports for moving the same upon adjustment in position of said dresser support, and means including a piston and cylinder type fluid actuator for altering the effective length of said mechanical connection between two limits corresponding to two limit positions of said piston within its cylinder to thereby shift said movable one of said first pair of supports independently of said dresser supp rt.

'7. In a grinding machine, thecombination of a base, work and wheel supports, the latter carrying a rotatively driven grinding wheel, means pivotally mounting said work support on said base for rocking motion of said work support transaxially of said wheel, a dresser support adjustable toward and from said wheel, means mechanically connecting said dresser support to said work support for rocking of the latter upon adjustment in position of said dresser support, and means including a piston and cylinder type fluid actuator for altering the effective length of said mechanical, connection between two limits corresponding to two limit positions of said piston within its cylinder, to thereby shift said work support with reference to said grinding wheel independently of adjustment in position of said dresser support.

. 8. In a grinding machine, the combination of a base having relatively movable work and wheel supports mounted thereon, the latter carrying a rotatively driven grinding wheel, a screw having a nut threaded thereon with said nut restrained against rotation and free for endwise movement with reference to said base, size control means for revolving said screw, first connecting means for connecting said nut to one of said supports to shift the latter with reference to the other sup port upon endwise displacement 'oi'-said-nut, a dresser support adjustable toward and from said wheel, a second connecting means for connect-. ing said dresser support to said screw to displace the latter endwise in accordance with movement of said dresser support, and a connector extensible or contractible at will interposed in said second connecting means and including a fluid actuated piston and cylinder.

9. In a, grinding machine, the combination of a base having relatively movable work and wheel supports mounted thereon, the latter carrying a rotatively driven grinding wheel, a screw having a nut threaded thereon with said nut-restrained against rotation and free for endwise movement with reference to said base, size control means for revolving said screw, first connecting means for connecting said nut to one of said supports to shift the latter wtih reference to the other support upon endwise displacement of said nut, a

dresser support adjustable toward and from said wheel, a second connecting means for connecting said dresser support to said screw to displace the latter endwise in accordance with movement of said dresser support, and a connector of controllable length including a fluid. actuatedtpiston and cylinder interposed in one of said connecting means.

10. In a grinding machine, the combination of work and wheel supports having means thereon for respectively revolvably supporting a work piece and a grinding wheel, means pivotally mounting at least one of said supp rts for rocking motion of the same transversely of the work, a dresser, means supporting said dresser for adjusting motion generally transaxially of, a grinding wheel carried by said wheel support, and means for effecting rocking motion of said pivoted mounting means proportionate to the motion of said dresser supporting means.

11. In a grinding machine, the combination of a. base having a, wheel support thereon carrying a rotatively driven grinding wheel, work and dresser supports located on substantially opposite sides of said wheel, means pivoting said work support on said base for rocking motion of the work carried by the work support generally transaxially of said wheel, me'ans mounting said dresser support on said base for straight line in and out motion of the same withreference to said wheel in a direction substantially transaxial of the latten and means for automatically rocking said work support through angular distances proporable toward and from said wheel, and means for tilting said support toward the wheel coincident with, and through a distance proportionate to.

each advance of said dresser support toward said wheel. a

13. In a grinding machine, the combination of a base, a 'work support, a wheel support having a rotatively driven grinding wheel thereon, means pivotally mounting at least one of said supports on said base for rocking motion toward and away from the other generally transaxially of said wheel, means-for adjustably securing said wheel said wheel and wheel support anzularly with ref erence to a work piece carried by said work support, a dresser support movably mounted on said wheel support, means for adjusting said wheel support toward and from said wheel, and means for automatically rocking a pivotally mounted one of said work and wheel supports through a distanoe proportionate to each change in position of said dresser support.

' AUGUST F. MARKUS. 

